This application claims the benefit of a Japanese Patent Application No. 2000-159986 filed May 30, 2000, in the Japanese Patent Office, the disclosure of which is hereby incorporated by reference.
1. Field of the Invention
The present invention generally relates to information storage apparatuses, and more particularly to an information storage apparatus, such as an optical disk unit and an optical card unit, which records, reproduces and/or erases information with respect to a recording medium such as an optical disk and an optical card, by converging a light beam from a semiconductor laser on the recording medium.
2. Description of the Related Art
As a first example of a conventional information storage apparatus, there is an optical disk unit which records, reproduces and/or erases information with respect to a plurality of kinds of optical disks. When recording the information in such an optical disk unit, it is extremely important that the optical disk is in a state under a stable servo, in order to avoid a write error caused by a servo error.
However, a servo signal may be distorted due to various external disturbances, and an off-servo state may occur.
Particularly when a rate at which the information is to be recorded becomes high, it becomes more difficult to carry out a stable servo.
Accordingly, an information storage apparatus which is provided with a means for reducing a light emission power of a laser diode or turning OFF the laser diode when the off-servo state occurs and a servo error is detected during the recording, so as to avoid an erroneous recording, has been proposed in a Japanese Laid-Open Patent Application No. 5-298736, for example.
As a second example of the conventional information storage apparatus, there is an optical disk unit which records, reproduces and/or erases information with respect to a plurality of kinds of optical disks. When recording the information in such an optical disk unit, it is extremely important that ATIP information included in the optical disk is accurately detected and decoded, in order to accurately perform a positioning with respect to the information which is to be recorded, and to synchronize the information which is to be recorded with respect to a rotational speed of the optical disk.
However, because a signal level of the ATIP signal is extremely small, it may be difficult to detect the ATIP signal due to various external disturbances.
Particularly when a rate with which the information is to be recorded becomes high, it becomes more difficult to detect the ATIP signal.
Accordingly, an information storage apparatus which is provided with a means for correcting a tracking error when an ATIP error rate increases during the recording, so as to reduce the ATIP error rate, has been proposed in a Japanese Laid-Open Patent Application No. 5-151600, for example.
As a third example of the conventional information storage apparatus, there is an optical disk unit which records, reproduces and/or erases information with respect to a plurality of kinds of optical disks. When recording the information in such an optical disk unit, it is important that the recording is carried out continuously without a recording error. For example, the recording error is caused by a shock, vibration or the like.
Accordingly, an information storage apparatus which is provided with a means for interrupting the recording of information when the shock, vibration or the like is detected, has been proposed in a Japanese Laid-Open Patent Application No. 11-328830, for example.
As a fourth example of the conventional information storage apparatus, there is an optical disk unit which records, reproduces and/or erases information with respect to a plurality of kinds of optical disks. When a temperature of such an optical disk unit, particularly a temperature of an optical system portion called an optical pickup, rises, a light emission characteristic of the laser diode which is used for recording the information may change, and an error may be generated during the recording. In addition, even if no error is generated during the recording, a recording quality may be deteriorated by the temperature rise. As a result, there is a possibility of recording an optical disk from which the information cannot be reproduced.
Furthermore, in a high temperature state, it is necessary to increase the light emission power of the laser diode in order to continue recording the information without deteriorating the recording quality, but a serviceable life of the laser diode may be shortened by the increased light emission power.
Accordingly, an information storage apparatus which is provided with a means for changing a converging state of a laser spot by multiplexing with a focus servo when a high temperature is detected during the recording, has been proposed in a Japanese Laid-Open Patent Application No. 8-306052, for example.
But in the first example of the conventional information storage apparatus, although it is possible to prevent an erroneous recording on the track by suppressing the light emission of the laser diode at a light emission power which would record information when the servo error is generated, there was a first problem in that the data recorded up to that point in time cannot be utilized.
Particularly in the case of a write-once optical recording medium, such as a CD-R, which can only be recorded with information once, a storage capacity of the optical recording medium may be wasted, and a time used to make the recording up to that point in time may be wasted.
On the other hand, in the above described information storage apparatus, the servo errors include a servo error detected by the tracking error signal.
When the tracking error signal detects the servo error, the focus servo may be in an on-servo state and stable. For this reason, if all of the servos are once turned OFF and then turned ON to obtain the on-servo states, there was a second problem in that it may take too much time for the servos to stabilize.
Further, in the above described information storage apparatus, when the information recording is interrupted upon detection of the servo error and the recording is to be resumed so that there is no discontinuity with the data recorded immediately before the recording was interrupted, there is a possibility that the information is recorded in the off-servo state if the servo error is actually generated. As a result, there was a third problem in that there is a possibility of deteriorating the recording quality of the optical recording medium which is recorded with the information.
Next, in the above described information storage apparatus, when the information recording is interrupted upon detection of the servo error and the recording is to be resumed so that there is no discontinuity with the data recorded immediately before the recording was interrupted, the cause of the servo error may be dependent on the rotational speed of the optical recording medium on which the information is to be recorded.
In this case, even if the information recording is interrupted upon detection of the servo error and the recording is resumed so that there is no discontinuity with the data recorded immediately before the recording was interrupted, the servo error is generated again, and a loop for interrupting and resuming the information recording is repeated, and there was a fourth problem in that the information recording may not end.
Moreover, in the above described information storage apparatus, when the information recording is interrupted upon detection of the servo error and the recording is to be resumed so that there is no discontinuity with the data recorded immediately before the recording was interrupted, there was a fifth problem in that the time finally required to record the information may become extremely long if the recording rate is changed at the first detection of the servo error, in a case where the cause of the servo error detection is other than the rotational speed of the optical recording medium.
On the other hand, in the second example of he conventional information storage apparatus, it is possible to reduce the ATIP error rate caused by the tracking error, but there is no effect on the ATIP error rate which increases due to other causes. In some cases, there was a sixth problem in that the recording is performed out of synchronism with respect to the rotational speed of the optical recording medium and a write error may be generated if the situation becomes worse.
Particularly in the case of the write-once optical recording medium, such as the CD-R, which can only be recorded with information once, the recording capacity of the optical recording medium may wasted if the write error occurs, and the time used to make the recording up to that point in time may also be wasted.
In the above described information storage apparatus, one of the causes which increase the ATIP error rate is determined by a relative position (hereinafter referred to as a lens position) of an objective lens of the optical pickup with respect to a carriage which moves the objective lens, an actuator or the like in a radial direction of the optical recording medium.
In other words, even if the ATIP error rate increases and the information recording is interrupted and resumed, there are cases where the information recording is resumed from the position of the objective lens identical to that immediately before the recording was interrupted if the carriage did not move from immediately before the interruption of the recording. In such cases, the ATIP error rate immediately after the recording is resumed is high, and the interruption and resuming of the information recording are repeated. As a result, there was a seventh problem in that the information recording may not end.
Next, in the above described information storage apparatus, when the information recording is interrupted upon detection of the increase of the ATIP error rate and the recording is to be resumed so that there is no discontinuity with the data recorded immediately before the recording was interrupted, there are cases where the increase of the ATIP error rate is dependent on the rotational speed of the optical recording medium on which the information is to be recorded. In such cases, the ATIP error rate is large for the same recording rate, even if the information recording is interrupted and resumed as the ATIP error rate increases. Consequently, there was an eighth problem in that the interruption and resuming of the information recording are repeated, and the information recording may not end.
On the other hand, in the above described information storage apparatus, when the information recording is interrupted upon detection of the increase of the ATIP error rate and the recording is to be resumed so that there is no discontinuity with the data recorded immediately before the recording was interrupted, there was a ninth problem in that the time finally required to record the information may become extremely long if the recording rate is changed at the first detection of the increase of the ATIP error rate, in a case where the cause of the increased ATIP error rate is other than the rotational speed of the optical recording medium.
In the third example of the conventional information storage apparatus, in the case of the write-once optical recording medium, such as the CD-R, which can only be recorded with information once, there was a tenth problem in that the recording capacity of the optical recording medium may wasted and the time used to make the recording up to that point in time may also be wasted, if the recording is interrupted due to the shock, vibration or the like.
Next, in the above described information storage apparatus, if the shock, vibration or the like is due to external causes, the shock, vibration or the like will be eliminated when the external causes are eliminated, to thereby enable the information recording to be resumed stably. However, if the shock, vibration or the like is due to internal causes such as a cause due to the rotational speed of the optical recording medium, the shock, vibration or the like is generated under the same conditions even when the information recording is resumed, and the interruption and resuming of the information recording may be repeated. Consequently, there was an eleventh problem in that the final recording rate may become low, and the information recording may not be resumed and completed.
Moreover, in the above described information storage apparatus, when the information recording is interrupted upon detection of the shock, vibration or the like and the recording is to be resumed so that there is no discontinuity with the data recorded immediately before the recording was interrupted, there was a twelfth problem in that the time finally required to record the information may become long if the recording rate is changed at the first detection of the shock, vibration or the like, in a case where the shock, vibration or the like is temporary because such temporary shock, vibration or the like will not be generated again.
In addition, in the above described information storage apparatus, there was a thirteenth problem in that a shock sensor is required in general to detect the shock, vibration or the like, and a redundant circuit associated therewith needs to be added.
Next, in the fourth example of the conventional information storage apparatus, an operating range of the focus servo is finite, and the converging state of the light beam can only be controlled to a predetermined level even when multiplexing is employed. Hence, the converging state cannot be controlled with respect to a temperature change in a range in which the change exceeds the predetermined level, and there was a fourteenth problem in that the recording quality deteriorates and the recording error occurs.
Particularly in the case of a write-once optical recording medium, such as the CD-R, which can only be recorded with information once, the storage capacity of the optical recording medium may be wasted, and the time used to make the recording up to that point in time may be wasted.
Moreover, in the above described information storage apparatus, if the temperature upon starting of the information recording is high from the initial state, the temperature detected during the recording naturally becomes high. For this reason, the detected temperature easily becomes greater than a predetermined high temperature, and there was a fifteenth problem in that there are possibilities that pause and rewrite of the information recording will occur frequently, and that the write will not be completed in a worst case under the high-temperature condition.
On the other hand, if the initial temperature is extremely low, there is a possibility that the recording quality will deteriorate before the predetermined high temperature is reached.
In addition, in the above described information storage apparatus, the detection of the high temperature may be caused mainly by the light emission of the laser diode which is used for the information recording and urges a temperature rise of the optical pickup. Furthermore, as the recording rate becomes high, the light emission power of the laser diode required for the information recording becomes high, and the temperature easily rises.
In other words, when the information recording is interrupted upon detection of the internal temperature rise due to the high light emission power of the laser diode required because of the high recording rate and the recording is to be resumed so that there is no discontinuity with the data recorded immediately before the recording was interrupted, there was a sixteenth problem in that the interruption and resuming of the information recording are repeated, and the information recording may not end. That is, the temperature rise occurs again for the same recording rate even when the information recording is interrupted by the temperature rise and resumed, if the cause of the temperature rise is dependent on the rotational speed of the optical recording medium on which the information is to be recorded.
Furthermore, in the above described information storage apparatus, if the cause of the detected high temperature is other than the rotational speed of the optical recording medium, the cause is not eliminated by reducing the rotational speed upon the first detection of the high temperature. Consequently, the high temperature is reached again, which results in the interruption of the recording and resuming of the recording at a reduced rotational speed, and there was a seventeenth problem in that the recording rate of the information recording may becomes extremely low.